<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
<script>
    var a = [], o = {};
    a.length;//0

    a[0] = 1;
    a[1] = 2;
    o[0] = 1;
    a.prop = 2;//注意此处，prop是不能
    console.log(a);
    o.prop = 2;
    console.log(o);
    console.log(o.prop);
//    console.log(o[prop]);
</script>
</body>
</html>